The present invention relates to the expansion of current microscopes by one or more wavefront modulators in the observation beam path and/or illumination beam path of a microscope. The modulator(s) purposely change(s) the phase and/or the amplitude of the light in such a way that a displacement and shaping of the focus in the object space and a correction of possible aberrations is achieved. The possible areas of use include confocal microscopy, laser-assisted microscopy, conventional light microscopy and analytic microscopy.
The following are patents relate to the present invention:
U.S. Pat. No. 4,408,874, W. Zinky, L. Rosenberg (1981/83):
Mechanically or pneumatically deformable optical element for astigmatic magnification adjustment for imaging systems in lithography.
EPO 0098969 B1, J. Arnaud (1983/87):
Deformable optical element for astigmatic correction. The thickness of the mirror membrane varies over the surface so that the membrane adopts a previously calculated shape when subjected to external bending forces.
EPO 0307354 B1, H. Choffat (1988/92):
Ring arrangement of bimorphic piezo layers for axial precision adjustment of components, e.g., microscope objectives.
U.S. Pat. No. 5,142,132, B. MacDonald, R. Hunter, A. Smith (1990/92):
Adaptively controlled optical system for wafer fabrication (stepper). The adaptive element controls the focus and corrects aberrations. The error signal for correction is obtained from the light reflected back from the wafer through interference with the original light. An exact method for correction of aberrations is not indicated.
DP DE 3404063 C2, A. Suzuki, M. Kohno (1984/93):
Curved transparent membrane in the beam path of an imaging system for correction of imaging errors, especially lateral focus offset.
U.S. Pat. No. 5,504,575, R. Stafford (1993/96):
Spectrometer based on spatial light modulator and dispersing element. Uses fibers and optical switches/flexible mirrors to switch the light to the detector after passing through the dispersing element.
EPO 167877, Bille, Heidelberg Instruments (applied for 1985):
Ophthalmoscope with adaptive mirror.
Definition of Terminology:
Definition of xe2x80x9cwavefront modulatorxe2x80x9d:
Within the meaning of the invention, a device for deliberately influencing the phase and/or the amplitude of a light wave. Based on a reflecting optical element (deformable mirror, electrostatic control, or controlled by a piezo array, or as a bimorphic mirror) or a transmitting optical element (LCD or similar unit). It can be built in a continuous or segmented manner. In particular, the segments can be adapted for controlling the respective problem.
Definition of aberrations in the microscope:
The aberrations of the microscope objective occurring in defocussed operating mode can basically be categorized as correctable or not correctable. Causally, the aberrations can be divided into aberrations caused by the objective, aberrations caused by the additional imaging optics of the microscope, and, finally, those caused by the preparation itself.
Controlling the wavefront modulator:
Controlling the wavefront modulator by a computer with appropriate software. The required correcting variables are either calculated beforehand (offline) or are calculated from measured quantities (online, e.g., through a wavefront sensor or by measuring the point brightness in the intermediate image).
In conventional light microscopy, as well as in laser-assisted microscopy, the focus of the objective must be displaced with high precision along the optical axis as well as laterally. In conventional microscopes, this is carried out by mechanical displacement of the object stage or objective. In addition, in case of illumination by laser radiation, displacements are also necessary in the object space. Consequently, there is a need for three-dimensional focus control in the object space.
Based on the principle of the microscope, these displacements can also be carried out at the wavefront of the beam path. However, this manipulation must take place in a pupil plane of the beam path. Axial displacement of the focus in the object corresponds to a spherical change in the wavefront, lateral displacement of a tilt of the wavefront. Also, aberrations in the beam path can be compensated by changing the wavefront.
It is an object of the present invention to displace and shape the focus in the object space in an improved manner over that of previous devices. If is a further object of the present invention to correct aberrations in an improved manner.
In accordance with the invention, the above objects are carried out by placing one or more wavefront modulators in the observation beam path and/or illumination beam path of a microscope.